In most firefighting scenarios involving class “B”
materials requiring the application of mechanical foam,
the mechanical foam nozzle (MFN) was used. The MFN had a
corrugated rubber body with a 1 ½-inch inlet, and was 2
by 44 inches in length. It had no control valve; water
had to be turned on or off at the control valve for the
MFN hose line. The MFN was attached to the foam line
fire hose with the Navy pick-up unit (NPU). The MFN was
used to pick up foam solution from a nearby can of
mechanical foam liquid. Foam could also be introduced at
the pump with a NPU or an in-line eductor. The 6% foam
solution was prepared by mixing the foam-forming liquid
with a water stream passing through a hose or pipe. Foam
production occurred at the terminal nozzle, which was
designed so that air was introduced, causing the
foam-water mixture to expand by forming large quantities
of air bubbles. The MFN had a chain that could be pulled
and set to hold the flexible corrugated rubber body at a
45- or 60-degree angle. This may have been done to goose
neck the nozzle under deck grating while fighting a
bilge fire. |
